Triphasic ictal scalp EEG pattern in interhemispheric onset seizures
Abstract number :
2.005
Submission category :
3. Neurophysiology / 3A. Video EEG Epilepsy-Monitoring
Year :
2016
Submission ID :
195458
Source :
www.aesnet.org
Presentation date :
12/4/2016 12:00:00 AM
Published date :
Nov 21, 2016, 18:00 PM
Authors :
Mitsuyo Nishimura, Seirei Hamamatsu General Hospital; Tohru Okanishi, Seirei Hamamatsu General Hospital, Hamamatsu, Japan; Hirotaka Motoi, Seirei Hamamatsu General Hospital; Takuya Yokota, Seirei Hamamatsu General Hospital; Keishiro Sato, Seirei Hamamatsu
Rationale: There were various ictal EEG patterns reported for patients with focal onset seizures. Mesial temporal lobe epilepsy was well known to show the specific ictal EEG patterns. Among extra-temporal lobe epilepsy, seizures starting from the interhemispheric cortex have a difficulty to understand their evolutions on ictal scalp video EEG (vEEG), because of spreading matters. We report the specific ictal scalp vEEG patterns in patients with ictal onset zone (IOZ) in the interhemispheric cortex. Methods: We collected 39 patients (age, 8-59 year-old; mean, 31) whose IOZ was confirmed using intracranial vEEG between 2012 and 2014. The duration of seizure ranged 3 to 56 years with a mean of 15 years. We analyzed the ictal pattern on the scalp vEEG between the interhemispheric onset seizures and the others. Results: Ten (26%) patients showed IOZ in the interhemispheric cortex. Eleven (28%) and 18 (16%) patients showed IOZ in extratemporal convexity and medial temporal area, respectively. We noticed the ictal triphasic pattern on scalp vEEG in 10 patients; phase 1, diffuse spike/fast wave; phase 2, diffuse voltage attenuation; phase 3, focal rhythmic evolutional pattern. Nine of 10 patients with ineterhemispheric IOZ showed the ictal triphasic pattern, phase 1->2->3 (sensitivity, 90%). The remaining one patient showed the evolution of phase 2->3. Twenty-eight of 29 patients with other IOZ did not show the complete evolutional triphasic pattern (specificity, 97%). Among the 28 patients with other IOZ, the evolution of phase 1->3 was seen in 2 patients, the evolution of phase 2->3 in 6 patients, and only phase 3 in 19 patients. The remaining one patient did not show ictal EEG change. The evolutional triphasic-EEG pattern was significantly correlated with IOZ in the interhemispheric cortex (p < 0.01). Conclusions: The evolutional triphasic-scalp EEG pattern may be a specific ictal change in seizure starting from the interhemispheric cortex. The ictal triphasic pattern of scalp EEG and seizure semiology reveal the mechanism of the seizure propagation from the interhemispheric cortex. Funding: none
Neurophysiology